I would suggest to split up the language settings from the dateTime settings.
The specific issue I'm talking about is the en_US language setting. This language uses US time settings of weeknumbers. These are different than the ones in Europe.
Since most apps and modules use en_US as a default language, it would be really nice to separate these two and use the weeknumbering of your choice (or maybe even depending on the local time of the user) instead of having to use the US weeknumbering or having to translate everything to en_UK in order to be able to use the European weeknumbering.
I stress how important this is. Especially for international companies in Germany, this always causes massive problems.